System and method for automated x-ray inspection

Abstract

An automated X-ray inspection system employing phase shift profilometry (PSP) and three dimensional (3D) surface modeling for improving inspection of an object, includes at least one projector for projecting light to the object, at least one optical lens for imaging a light pattern obtained from the object to at least one camera, the at least one camera being adapted to capture a plurality of images of the object. The light passing from the projector lens of the at least one projector illuminates the object thereby generating the light pattern to be imaged from the object to the at least one camera via the at least one optical lens.

We claim: 
     
       1. An automated X-ray inspection system employing phase shift profilometry (PSP) and three dimensional (3D) surface modeling for improving inspection of an object, said system comprising:
 at least one projector for projecting light to said object, said at least one projector comprising a projector lens; 
 at least one optical lens for imaging a light pattern obtained from said object to at least one camera, said at least one camera being adapted to capture a plurality of images of said object; 
 wherein light passing from said projector lens of said at least one projector illuminates said object thereby generating said light pattern to be imaged from said object to said at least one camera via said at least one optical lens; 
 a calibration plate for calibrating a plurality of parameters of said object; and 
 a 3D surface interpolator to evaluate height information associated with said object and generate a complete surface profile of said object. 
 
     
     
       2. The system as claimed in  claim 1 , wherein said plurality of parameters comprises height, position, and magnification. 
     
     
       3. The system as claimed in  claim 1 , wherein said at least one projector is configured to project at least one of a fringe pattern to said object and a structured white light pattern to said object. 
     
     
       4. The system as claimed in  claim 1 , wherein said 3D surface interpolator is a global surface model (GSM) to inspect said object and said global surface model (GSM) use a thin-plate spline (TPS) method for evaluating surface interpolation of said object. 
     
     
       5. The system as claimed in  claim 1 , wherein said 3D surface interpolator is a Local Surface Model (LSM) to inspect said object and said Local Surface Model (LSM) use Predictive Slice Height (PSH) to estimate a z-height of at least one of a particular joint and solder of said object by taking an average z-height value of all its close neighbor focused joints for evaluating surface interpolation of said object. 
     
     
       6. The system as claimed in  claim 1 , wherein said at least one projector is a Pico Projector or equivalent means. 
     
     
       7. The system as claimed in  claim 6 , wherein said at least one pico-projector is implemented by DLP (digital light processing) technology. 
     
     
       8. The system as claimed in  claim 1 , wherein said at least one optical lens comprises a fixed-focus lens. 
     
     
       9. The system as claimed in  claim 8 , wherein means for focusing are arranged telecentrically with respect to said structured white light pattern. 
     
     
       10. The system as claimed in  claim 9 , wherein said means for focusing are a fixed focal length operative to provide at least one image of structured white light pattern from said object to said at least one camera. 
     
     
       11. The system as claimed in  claim 1 , wherein said system further comprises a data processing device for computing a plurality of phase shift values of said object with respect to a reference plane. 
     
     
       12. The system as claimed in  claim 11 , wherein said data processing device comprises a memory to collect said plurality of phase shift values of said object and a processor comprising at least one module to determine and measure surface profile of at least one object for a plurality of preselected regions. 
     
     
       13. The system as claimed in  claim 12 , wherein said measured surface profile of said at least one object for said plurality of preselected regions is provided to said 3D surface interpolator for interpolation and generating a global board warpage matrix. 
     
     
       14. The system as claimed in  claim 1 , wherein a partial surface profile of said object and/or said complete surface profile of said object are provided for reconstructing and generating a plurality of 3D image slices by utilizing tomosynthesis. 
     
     
       15. The system as claimed in  claim 1 , wherein said object is a PCB and said at least one camera operates in line scan mode or area scan mode. 
     
     
       16. A method for improving inspection of an object by an automated X-ray inspection system employing phase shift profilometry (PSP) and three dimensional (3D) surface modeling, said method comprising the steps of:
 projecting light from at least one projector comprising a projector lens to said object; 
 imaging a light pattern obtained from said object by employing at least one optical lens to at least one camera for capturing a plurality of images of said object; 
 wherein light passing from said projector lens of said at least one projector illuminates said object thereby generating said light pattern to be imaged from said object to said at least one camera via said at least one optical lens; 
 calibrating a plurality of parameters of said object by a calibration plate; and 
 evaluating height information associated with said object by a 3D surface interpolator and generating a complete surface profile of said object. 
 
     
     
       17. The method as claimed in  claim 16 , wherein said plurality of parameters comprises height, position, and magnification. 
     
     
       18. The method as claimed in  claim 16 , wherein method further comprises projecting a structured white light pattern from said at least one projector to said object. 
     
     
       19. The method as claimed in  claim 16 , wherein said method further comprised arranging means for focusing telecentrically with respect to said structured white light pattern. 
     
     
       20. The method as claimed in  claim 19 , wherein said means for focusing are a fixed focal length operative for providing at least one image of structured white light pattern from said object to said at least one camera. 
     
     
       21. The method as claimed in  claim 16 , wherein said method further comprises computing a plurality of phase shift values of said object with respect to a reference plane by employing a data processing device. 
     
     
       22. The method as claimed in  claim 21 , wherein said method further comprises collecting said plurality of phase shift values of said object in a memory, and determining and measuring surface profile of at least one object for a plurality of preselected regions by a processor comprising at least one module. 
     
     
       23. The method as claimed in  claim 22 , wherein said method further comprises providing said measured surface profile of said at least one object for said plurality of preselected regions to said 3D surface interpolator for interpolation and generating a global board warpage matrix. 
     
     
       24. The method as claimed in  claim 23 , wherein said 3D surface interpolator is a global surface model (GSM) to inspect said object and said global surface model (GSM) use a thin-plate spline (TPS) method for evaluating surface interpolation of said object. 
     
     
       25. The method as claimed in  claim 23 , wherein said 3D surface interpolator is a Local Surface Model (LSM) to inspect said object and said Local Surface Model (LSM) use Predictive Slice Height (PSH) to estimate a z-height of at least one of a particular joint and solder of said object by taking an average z-height value of all its close neighbor focused joints for evaluating surface interpolation of said object. 
     
     
       26. The method as claimed in  claim 16 , wherein said method further comprises providing said complete surface profile of said object for reconstructing and generating a plurality of 3D image slices by utilizing tomosynthesis. 
     
     
       27. The method as claimed in  claim 16 , wherein said method further comprises operating said at least one camera in line scan mode or area scan mode.